Stairs 1 wooden staircase 3D print model

Stairs, staircase, stairway, stairwell, and flight of stairs are all names for a construction designed to bridge a large vertical distance by dividing it into smaller vertical distances, called steps. Stairways may be straight, round, or may consist of two or more straight pieces connected at angles.

Special stairways include escalators and ladders. Alternatives to stairways are elevators and inclined moving sidewalks. The step is composed of the tread and riser.

tread - The part of the step that is stepped on. It is constructed to the same specifications (thickness) as any other flooring. The tread length is measured from the outer edge of the step to the vertical riser between steps. riser - The vertical portion of the step between steps. This may be missing for an open stair effect. nosing - An edge part of the tread that protrudes from the riser beneath. If it is present, this means that horizontally, the total run length of the stairs is not simply the sum of the tread lengths, the treads actually overlap each other slightly bullnose - Where stairs are open on one or both sides, the first step above the lower floor may be wider than the other steps and rounded. The rounded portion of the step is called a bullnose. A double bullnose can be used when both sides of the stairs are open. winders - Winders are steps that are narrower on one side than the other. They are used to change the direction of the stairs without landings. A series of winders form a circular or spiral stairway. When three steps are used to turn a 90° corner, the middle step is called a kite winder due to its similarity to a diamond-shaped kite. stringer, stringer board or sometimes just string - The structural member that supports the treads. There are typically two stringers, one on either side of the stairs; though the treads may be supported many other ways. trim - Trim (e.g. quarter-round or baseboard trim) is normally applied where walls meet floors. Within a flight of stairs there is no trim as the trim thickness will significantly eat into the tread width. Shoe moulding may be used between the lower floor and the first riser. Trimming a bullnose is a special challenge as the last riser above the lower floor is rounded. Today, special flexible, plastic trim is available for this purpose. Scotia is concave moulding that is underneath the nosing between the riser and the tread above it.